Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762527AbWLKFqn (ORCPT ); Mon, 11 Dec 2006 00:46:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762528AbWLKFqn (ORCPT ); Mon, 11 Dec 2006 00:46:43 -0500 Received: from e4.ny.us.ibm.com ([32.97.182.144]:60405 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762524AbWLKFqm (ORCPT ); Mon, 11 Dec 2006 00:46:42 -0500 Date: Mon, 11 Dec 2006 11:15:45 +0530 From: Srivatsa Vaddagiri To: Andrew Morton Cc: Ingo Molnar , Bjorn Helgaas , linux-kernel@vger.kernel.org, Myron Stowe , Jens Axboe , Dipankar , Gautham shenoy Subject: Re: workqueue deadlock Message-ID: <20061211054545.GC5339@in.ibm.com> Reply-To: vatsa@in.ibm.com References: <20061207105148.20410b83.akpm@osdl.org> <20061207113700.dc925068.akpm@osdl.org> <20061208025301.GA11663@in.ibm.com> <20061207205407.b4e356aa.akpm@osdl.org> <20061209102652.GA16607@elte.hu> <20061209114723.138b6e89.akpm@osdl.org> <20061210082616.GB14057@elte.hu> <20061210004318.8e1ef324.akpm@osdl.org> <20061210114943.GA14749@elte.hu> <20061210041600.56306676.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061210041600.56306676.akpm@osdl.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1034 Lines: 23 On Sun, Dec 10, 2006 at 04:16:00AM -0800, Andrew Morton wrote: > One quite different way of addressing all of this is to stop using > stop_machine_run() for hotplug synchronisation and switch to the swsusp > freezer infrastructure: all kernel threads and user processes need to stop > and park themselves in a known state before we allow the CPU to be removed. > lock_cpu_hotplug() becomes a no-op. Well ...you still need to provide some mechanism for stable access to cpu_online_map in blocking functions (ex: do_event_scan_all_cpus). Freezing-tasks/Resuming-them-after-hotp-unplug is definitely not one of them (when they resume, online_map would have changed under their feet). > Dunno if it'll work - I only just thought of it. It sure would simplify > things. -- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/